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INSTRUCTION MANUAL
Providing Exceptional Consumer Optical Products Since 1975
Orion
®
BT70 Binocular Telescope
#9547
IN 307 Rev. B 02/09
Figure 1. The Orion BT70 Binocular Telescope.
Handle
IP Knob (not visible)
Diopter scale
Lens shades (retracted)
Mounting plate (not visible)
Dovetail holder for handle
Eyepiece holders
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The BT70 is a true binocular telescope, with optical quality
and features you’d expect of a fine astronomical instrument.
The included eyepieces provide 20x magnification, but
optional interchangeable eyepieces (available from Orion)
let you vary the magnification for deep-sky, solar system,
and terrestrial viewing - with 3D-like depth of field! The 90°
eyepiece viewing angle makes nighttime observing more
comfortable, as the binoculars don’t need to be positioned
above your head when looking upwards. The rugged body
construction and waterproof design ensure the BT70’s will
provide viewing enjoyment for years to come.
Please take the time to read this instruction sheet before
using your new binoculars.
Using a Tripod
When observing with large-aperture binoculars like the
Orion BT70s, a sturdy photo tripod or altazimuth mount is
required. This is because the weight and magnification of
the binoculars make it impossible to hold them steady with
your hands.
To attach the BT70 to a photo tripod, simply thread the
tripod’s 1⁄4"-20 mounting stud into the threaded hole in the
BT70’s mounting plate. The tripod must be able to support
approximately 10 lbs., otherwise it may not be stable
enough for the BT70.
To attach the BT70 to an altazimuth mount that utilizes a
dovetail holder, like the Orion VersaGo mount, an optional
dovetail L-bracket is needed. The L-bracket connects to the
BT70’s mounting plate, and has a dovetail bar that goes
directly into the mount’s dovetail holder. Contact Orion to
order this optional L-bracket.
Inserting the Eyepieces
Perhaps the most unique feature of the BT70 is its ability
to change eyepieces. The two supplied eyepieces provide
a magnification of 20x, but other magnifications can be
obtained by purchasing optional eyepiece sets from Orion.
To install the eyepieces, first remove the cover caps from
the binoculars and eyepieces. Then, simply insert the
eyepieces into the binoculars’ eyepiece holders (Figure
1). Push the eyepieces into the holders until they are fully
seated. To remove the eyepieces, just pull the eyepieces
out of their holders.
Extending the Lens Shades
Another nice feature of the BT70 is its extendable lens
shades (Figure 1). These increase image contrast by
preventing glare (unwanted stray light) from entering the
objective lenses of the binoculars. They also slow the
formation of dew on the objective lens exteriors. To use the
lens shades, grasp them with your fingers, and pull them
outwards.
You will need to retract the lens shades to fit the binoculars
into its case.
Adjusting the Distance Between Your Eyes
(Interpupillary Distance)
Adjusting the interpupillary (IP) distance of the BT70 is
incredibly easy. Simply turn the chrome IP knob located
between the eyepieces. Rotate the knob until the distance
between the eyepieces matches the distance between your
eyes. When properly adjusted, you should see a single,
round field of view when looking through the binoculars.
Make this adjustment before you attempt to focus the
binoculars.
Focusing
The BT70 binoculars utilize individual focus eyepieces.
This makes the binoculars mechanically more rugged than
similar center-focus models, and generally maintains optical
alignment better. For astronomical observation, individual
focus eyepieces are usually preferred.
Pick an object in the distance to view. At night, best focus
will be achieved by focusing on a bright star. Cover your
right eye (or cover the right objective lens of the binocular)
and focus the left eyepiece by rotating the rubber grip ring
on the eyepiece holder it until the image appears clearest.
Then cover your left eye (or cover the left objective lens
of the binocular) and focus the right eyepiece by rotating
the eyepiece holder until the image appears clearest. The
binoculars are now focused. If you want to view an object
at a different distance, re-focusing of both eyepieces is
required. Also, changing eyepieces may require some slight
refocusing.
For astronomical observation, all objects will always appear
focused at the infinity focus point. This means you only
need to focus the binoculars once per observing session.
This also means you can take note of the diopter scale
(Figure 1) setting for each eyepiece when focused on an
astronomical object, and return to those settings when
observing another night. You will find this to be a great
convenience!
Congratulations on your purchase of a pair of quality Orion binoculars. The BT70 Binocular Telescope provides the
large light grasp you need for astronomical observation, but unlike a telescope, allows you to use both eyes simultaneously
for viewing. This results in better image resolution, contrast, and brightness than a similar sized telescope can provide.
WARNING Never look directly at the Sun
through your binoculars without professionally
made solar filters, even for an instant, or
permanent eye damage could result. Young
children should use these binoculars on sunny
days only with adult supervision.
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Since everyone’s eyes focus images slightly differently,
different observers will need to refocus the binoculars for
their own vision.
Fold-Down Eyeguards
BT70 binoculars feature fold-down eyeguards on the
eyepieces. The eyeguards are usually left in the up position
for use without eyeglasses, as this helps prevent glare
from entering between your eye and the eyepieces. To use
the binoculars with eyeglasses, you will need to fold the
eyeguards down in order to get your eyes close enough to
the eyepieces to see the entire field of view.
Waterproof Binoculars
The BT70 is nitrogen-purged and sealed to be waterproof
and internally fogproof. While it is impervious to rain, wind,
splashing, and humidity, do not immerse the binocular in
water under any circumstances. If the binocular becomes
wet with fresh water, merely blot it dry with a clean cloth and
clean the lens surfaces as outlined below. Saltwater should
be rinsed off completely and the binocular then blotted dry
and its lenses cleaned as outlined below. If the binocular
body becomes dirty, it can be cleaned with warm water and
a clean cloth. If extremely dirty, or oily, clean the body with
a dilute solution of warm water and mild soap on a cloth,
then rinse with clean water and blot dry. Do not clean lens
surfaces with soap and water!
Cleaning and Care of Binocular Lenses
The lens surfaces of Orion binoculars are coated with anti-
reflection multi-coatings that can be damaged with careless
handling. Avoid touching lens surfaces with fingers or any
coarse material. All optics, even if stored, should be cleaned
at least once a year or whenever they are dirty. The dust that
builds up on coatings promotes mold growth, which etches
glass and destroys coatings. Avoid over-cleaning; it can also
damage the coatings. Always use lens cleaning tissue and
fluid that are specifically designed for multicoated lenses. Do
not use fluids or tissues that are for eyeglasses or household
use. Never attempt to disassemble the binocular or eyepieces
in order to clean them; this can also void the warranty.
To clean the binocular (and eyepiece) lenses, first blow off
the lens with a blower bulb or gently wipe the lens with a lens
cleaning brush to remove the larger particles. Put a few drops
of lens cleaning fluid on a fresh piece of lens cleaning tissue
(never on the lens) and gently wipe the lens. Quickly wipe the
excess fluid with a new, dry piece of lens cleaning tissue. For
larger lenses, clean only a small area at a time, using a new
tissue each time. On excessively dirty lenses, wipe across the
lens using one stroke for each tissue, alternating wet and dry.
Always avoid excessive pressure or rubbing when wiping, as
wiping too hard can scratch the lens.
Storage and Transport
The BT70 binoculars come with a heavy-duty case for safe
storage and transport. We recommend always keeping the
binoculars in their case with the cover caps on when not in use.
The case has a lock on each latch for extra security. Use one of
the supplied keys to lock and unlock the latches. A removable
shoulder strap is also provided for ease of transport.
Avoid unnecessary shocks to the binocular, whether it is in its
case or not. Although the BT70 is designed to be mechanically
rugged, excessive impacts may cause the optics to become
misaligned. This is not covered by the warranty.
A metal carry handle is supplied with the BT70. This connects
to the dovetail holder on the binoculars, which is located just in
front of the eyepieces (Figure 1). Slide the handle’s base into
the dovetail holder, and secure it in place with the thumbscrew.
The handle comes in quite handy when attempting to mount
the BT70 onto a tripod. Before the BT70 can be placed into its
case, the handle must be removed.
Allow the optics to slowly adjust to cold weather by storing the
instrument (in its case) in a cold area, such as an unheated
garage or the trunk of a car, for a few hours before use. When
bringing the instrument back inside a warm house, open up
the case, remove the binoculars, remove the cover caps, and
let everything dry out. The binoculars should be stored in a
cool, dry place to prevent mold growth, which can damage the
optics. This is not covered by the warranty.
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One-Year Limited Warranty
This Orion BT70 Binocular Telescope is warranted against defects in materials or workmanship for a
period of one year from the date of purchase. This warranty is for the benefit of the original retail pur-
chaser only. During this warranty period Orion Telescopes & Binoculars will repair or replace, at Orion’s
option, any warranted instrument that proves to be defective, provided it is returned postage paid to:
Orion Warranty Repair, 89 Hangar Way, Watsonville, CA 95076.
This warranty specifically does not cover abuse, modification, mishandling, self-repair, or normal wear
and tear (including mold growth). Binocular collimation (alignment of the optics) is specifically not
covered beyond the 30-day return period. Binoculars go out of collimation only if they are dropped or
bumped. Binocular collimation (and cleaning) are considered routine maintenance and should be done
every five years, or when necessary.
If the product is not registered, proof of purchase (such as a copy of the original invoice) is required. This
warranty gives you specific legal rights, and you may also have other rights, which vary from state to
state. For further warranty service information, contact: Customer Service Department, Orion Telescopes.
Objective lenses: 70mm clear aperture, air-spaced
achromatic doublets
Magnification: 20x eyepieces included, other
magnification eyepieces
available from Orion
Focusing: Individual focus eyepieces
Field of view: 3.2° for the included eyepieces
Eye relief: 16mm for the included
eyepieces
Close focus: 50 feet
Prisms: BAK-4, porro, provide 90°
viewing angle
Anti-reflection coatings: Fully multi-coated
Eyeguards: Fold-down, rubber
Body design: All metal construction, single
piece body design, waterproof
Interior: Glare threaded, baffled,
blackened
Lens shades: Retractable
Weight: 8 lbs. 15 oz.
Mounting provision: 1⁄4"-20 mounting plate
Carry handle: Included, metal, removable
Dust covers: Metal covers for objective
lenses, rubber caps for
eyepieces and eyepiece holders
Case: Custom foam-lined hard carry
case included, removable
shoulder strap, 2x lock latches
with keys
Specifications
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